Deposition and characterization of silicon oxynitride material for the fabrication of optical waveguides

Despite the availability of high-speed microprocessors, the speed of the present day computers are becoming limited by copper interconnect time delay. Thus, to enhance bandwidth, waveguide optical interconnects are being investigated as replacements for present copper circuitry. In this research effort we have tried to design and fabricate silicon oxynitride waveguide structures. The silicon oxynitride films were deposited using silane (SiH 4) and nitrous oxide (N2O) source gases in a plasma enhanced chemical vapor deposition reactor. The flow-ratio, power level and the plasma drive frequency ratio were varied in order to optimize the deposition conditions for refractive index, growth rate, and stress. The refractive index and the thickness of the films were measured using a prism-coupling technique while the stress values were obtained from wafer bow measurements. To understand the material behavior, composition analysis was carried out using x-ray photoelectron spectroscopy analysis and elastic recoil detection analysis. In order to correlate the refractive index with film chemistry, high resolution XPS study was also carried out. It was observed that plasma drive frequency plays a major role in the film chemistry. Further material loss analysis also showed films deposited with lower drive frequency had improved transmission property compared to the films deposited with conventional higher drive frequency. Correlation of absorption loss data with film chemistry showed the low frequency films to have a higher percentage nitride character and less substoichiometric bonds. The low loss films were then utilized for fabrication of channel waveguide structures. Propagation loss data substantiated that these waveguide structures can be utilized for functionalized device applications. The details of this study are discussed in this dissertation.